GOOD NEWS. . . . The PICTURE UPLOAD FUNCTION IS WORKING !!! The tech folks at the parent company have been able to remedy the issue. You can upload pictures once again. Thank you for your patience.
It's a 1990 Mariner
The manual you need is Mercury manual # 90-857138R1
I would avoid aftermarket manuals if possible, stick with the OEM.
If you go to the Merc site, you can order manuals direct from them using the SN.